GB2316158A

GB2316158A - Refrigeration systems

Info

Publication number: GB2316158A
Application number: GB9616877A
Authority: GB
Inventors: Stephen David John George
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-08-10
Filing date: 1996-08-10
Publication date: 1998-02-18
Also published as: GB9616877D0

Abstract

A refrigeration system is designed to use electricity independently of its requirement to maintain a storage compartment in a range of temperatures. The system stores cold in a cold store which feeds the storage compartment when it is required. The system is controlled by a timer and a thermometer, which together balance the need for refrigeration against the need to switch the system on/off. To aid storage of cold in the cold store, the system includes a heat exchange unit so that a fluid with better heat storing characteristics can be used in the cold store. A cold storing material may be also be located in the top of the storage compartment to dampen any fluctuations in the temperature of the storage compartment.

Description

The specification of the two tier design for refrigeration units Description Title Two tier design for refrigeration units Technical field This invention relates to a new design for refrigeration units Background Refrigeration units are well known appliances. They come in many forms :- fridges, freezers, fridge freezers and conservators. However all these appliances will use electricity whenever the temperature of the storage compartment goes up above a certain point. This usually happens when the doors of the refrigeration units are opened and this happens during the day when the price of electricity is high. This design solves this problem by making and storing the coldness during the night, when the price of electricity is low, and using it during the day.

Essential technical features According to the present invention there is provided a two tier design for refrigeration unit comprising a cooling unit, an exchange unit, a storage unit, a storage compartment, a timer unit and a thermometer. The cooling unit being able to provide coldness for the system independently from the requirements of the storage compartment needing the coldness to keep items to be stored in the correct temperature range.

Detailed description Referring to fig 1 (page 10) which comprises of a cooling unit, an exchange unit, a storage unit, a storage compartment, a timer unit and a thermometer.

The main function of this invention is to allow the cooling unit to run independently or pohe needs of the storage compartment.

The cooler unit is the component which removes the heat from the system. It composes of a compressor, a dryer, a condenser and an evaporator. The cooler unit is controlled by a timer unit.

The exchange unit transfers the coldness from the cooling unit (refrigerant) to the fluid used for storage. The second fluids properties would be :1) A high specific heat. This means that the fluid will take more heat from the storage compartment to raise it by 1 "C and so more coldness can be stored in the same amount of fluid.

Thus reducing the amount of fluid needed to keep the items stored in their correct temperature range.

2) A high conductivity. This means that the fluid will quickly draw heat from the storage compartment. Thus improving the response time from the thermometer detecting that the items are outside the temperature range and the item being put back into that temperature range.

3) A high convection. This means that the fluid will quickly move around the unit and so reduce the need for any other form of pumping agent.

Warm fluid is taken from the top of the storage unit and cooled in the top of the exchange unit so that the density of the fluid increases and sinks to the bottom of the exchange unit. As it sinks down it is further cooled and the density of the fluid increases until it is pushed out into the bottom of the storage unit. This means the cooling unit is cooling the lower colder layers first (see figl) in the exchange unit before moving up and cooling the warmer fluid. This inhibits mixing as the colder fluid is cooled before the upper warmer layers and also means that the cooling unit refrigerant is at the highest possible temperature (i.e. the fluid at the top) when it comes out of the exchange and so improves efficiency of the cooling unit.

Warm fluid is taken from the top of the storage unit by the exchange and cold fluid is put in to the storage unit at the bottom. This will create a thermal layer in the storage unit which would stop the warm fluid at the top mixing with the cold fluid at the bottom.

The storage unit is where fluid is stored until it is needed. It is surrounded by cladding which is made of a poor heat conductor or a vacuum to prevent heat from entering the system The storage compartment is fed with the fluid from the storage unit via a valve. The valve is controlled by a thermometer which measures temperature inside the storage compartment.

The thermometer has four control temperatures State 1 Critically hot - Open valve. Override timer and turn cooling unit on.

State 2 Warm - Open valve and let more fluid in from the storage unit.

State 3 Cold - Shut valve no more fluid needed. Overridden by timer if on and therefore open valve.

State 4 Critically cold - Shut valve. Switch off cooling unit override timer.

If the thermometer is in state 3 and the timer is on then the valve is opened. This is to allow coldness not only to be stored in the storage unit but also to be stored in the storage compartment To enhance this a small amount of heat storing material is put in the top of the storage compartment. This material would either have a high specific heat and therefore need a lot of energy to heat it up (cool it down in this case) or would be a container with a fluid in it. The fluid would either freeze or boil at a certain point and therefore store coldness in the structure of the fluid. This has two advantages :1) A greater amount of coldness can be stored during the night in the storage compartment.

2) The heat storage material will smooth out the warming up and cooling cycle and therefore stop the unit from constantly swinging from too hot to too cold. i.e. it will act as a dampening agent.

If the door of the refrigeration unit it open (this can be detected with a switch in the door of the unit) and the thermometer changes state to 2 the thermometer would be overridden and the valve kept closed. This is to stop the system cooling air which will escape from the unit via the refrigerator door.

If the door of the refrigeration unit it open (this can be detected with a switch in the door of the unit) and the thermometer changes state to 1 the thermometer would not be overridden and the valve would be opened and an alarm could come on. This has two uses :1) If the door is left open by accident then the alarm will go off and hopefully someone will shut it.

2) If the refrigerator has reached a critical temperature and someone opens the door they will know that the refrigerators door needs to be closed as quickly as possible.

The storage compartment is fed from the bottom of the storage unit via convection currents. As the cool fluid sinks to the bottom of the storage compartment this pushes the warmer fluid up and out into the top of the storage unit. As the new cold fluid becomes warmer it will become less dense and therefore rise. This fluid rising will be replaced by new cold fluid from the storage unit.

In this process the storage unit is fed warm fluid to the top and cold fluid is removed from the bottom. Because colder fluid has a greater density it will stay at the bottom and the warm layer will stay at the top. This will create a thermal layer in the storage unit which would stop the warm fluid at the top mixing with the cold fluid at the bottom. This results in the storage unit being able to supply a quality supply of coldness throughout the day which has not been tainted by the fluid being brought in by the storage compartment Advantages 1) Electricity is used when it is at a less expensive rate and so the whole unit costs less to run.

2) The cooling unit will be run for much longer periods during the night and therefore items of equipment stay in their optimum working temperatures. Thus the cooling unit will generate coldness more efficiently and effectively.

3) The cooling unit will be run for much longer periods during the night and therefore items of equipment stay in their optimum working temperatures. Thus the reliability will be enhanced as the unit is not expanding and contracting as often.

4) In the event of a power cut the unit is less likely to be affected as the unit does not need electricity for long periods. This will result in less food being wasted and a lower chance of unit defrosting and spilling water all over the floor.

5) In the event of a power cut the unit is less likely to be affected as the unit does not need electricity for long periods. This will result in less insurance claims for food loss and so cheaper insurance.

6) In the event of a power cut the unit is less likely to be affected as the unit does not need electricity for long periods. This will result in less chance of food poisoning occurring as a result of the food defrosting and going bad before being re-frozen and then eaten by an unsuspecting person. It is dangerous to defrost and then re-freeze some foods.

Two tier design for refrigeration units Definitions Heat Energy which is in the form of vibrating molecules.

Coldness A lack of heat or where a substance which has had heat removed from it.

Specific heat The amount of energy required to raise a set amount of substance by a certain temperature.

Convection The ability to transfer heat via currents caused by changing density.

Conduction The ability to transfer heat by direct contact.

Refrigerant Fluid used in the cooling process.

Latent heat of fusion The heat required to melt a substance.

Latent heat of The heat required to boil a substance.

vaporisation Cooling unit Unit that removes heat from the system and puts it into the atmosphere.

Storage unit Unit that stores cold fluid until it is needed.

Storage compartment This is where the item(s) to be cooled are kept.

Item Thing which is to be kept in a set range of temperature. (e.g. food).

Exchange unit Allows heat to travel from one fluid to another without mixing occurring between the fluids.

Timer unit This unit detects when it is time to switch on the cooling unit when cheap electricity is available. The unit could be a timer or another device.

Timer off Timer unit is in the off state which means that cheap electricity is unavailable.

Timer on Timer unit is in the on state which means that cheap electricity is available.

Thermometer Unit that measures the temperature in the storage compartment.

Control - This is a range of temperatures measured by the thermometer and Temperature represent a state of the storage compartment i.e. OC to 6C maybe normal.

Claims

Claims

1) The two tier design for a refrigeration unit comprises of a storage unit, cooling unit, exchange unit and a storage compartment where the items to be refrigerated are kept wherein the cooling unit can run independently from the needs of the storage compartment by storing coldness until it is needed.

2) The two tier design for a refrigeration unit as in claim 1 wherein the cooling unit supplies the coldness to the storage unit via an exchange unit.

3) The two tier design for a refrigeration unit as in claim 1 wherein a timer unit and a thermometer control the operation of the cooling unit and the valves to the storage compartment.

4) The two tier design for a refrigeration unit as in claim 2 wherein the exchange means that there can be two different fluids. One in the cooling unit called refrigerant and one in the storage unit and storage compartment 5) The two tier design for a refrigeration unit as in claim 4 wherein the second fluid which is used in the storage area would have a high specific heat so that more "coldness" or lack of heat can be stored in the same amount of fluid.

6) The two tier design for a refrigeration unit as in claim 4 wherein the second fluid which is used in the storage area would have good conductivity. This is so that the transfer of heat energy to the storage compartment would be enhanced.

7) The two tier design for a refrigeration unit as in claim 4 wherein the second fluid which is used in the storage area would have good convection properties so that the fluid moves around the system without the need for pumping agents.

8) The two tier design for a refrigeration unit as in claim 1 wherein the cooling unit cools the bottom of the exchange unit before the top of the exchange unit. This is due to the refrigerant vaporising at the bottom first. Thus preventing mixing in the exchange unit as the cold gets much colder while higher up the exchange is cooled. This makes the cooling unit more efficient and effective as the refrigerant will be at the highest possible temperature when it exits the exchange unit. This is because the last fluid it is in contact with will be the warmest fluid. I.e. the fluid at the top of the exchange unit.

9) The two tier design for a refrigeration unit as in claim 1 and claim 8 wherein the storage unit is fed cold to the bottom of the unit from the exchange unit and warm/hot fluid is taken from the top of the unit by the exchange unit. Therefore using the lack of convection currents to form thermal layers so that the hot/warm fluid at the top does not mix with the cold fluid at the bottom.

10) The two tier design for a refrigeration unit as in claim 1 and claim 3 wherein the thermometer has four control states State 1 Critically warm - The storage compartment has become much too warm and there is a danger of damage to items in storage if this continues.

State 2 Warm - The storage compartment is outside its preferred range but there is no danger of damage to the items in storage.

State 3 Cold - The storage compartment is perfectly in its heat range.

State 4 Critically Cold - The storage compartment is too cold. Further cooling would damage the items or would not be economically viable.

11) The two tier design for a refrigeration unit as in claim 1, claim 3 and claim 10 wherein the thermometer is in state 1. The valve is opened and the timer unit has been overridden turning the cooling unit on to bring down the temperature of the storage compartment.

12) The two tier design for a refrigeration unit as in claim 1, claim 3 and claim 10 wherein the thermometer is in state 1. If the refrigerator door is open then an alarm will sound. This is detected by the standard light circuit which automatically comes on when the refrigerator door is opened via a switch.

13) The two tier design for a refrigeration unit as in claim 1, claim 3 and claim 10 wherein the thermometer is in state 2 and the door is closed. The valve is open to let fluid from the storage unit in to cool the storage compartment.

14) The two tier design for a refrigeration unit as in claim 1, claim 3 and claim 10 wherein the thermometer is in state 2 and the door is open. The valve would be shut. Therefore the storage compartment would not be cooled until the door was shut and thus not wasting energy trying to cool air which was moving from the storage compartment through the door.

15) The two tier design for a refrigeration unit as in claim 1, claim 3 and claim 10 wherein the thermometer is in state 3 and the timer is off. The valve is shut as no more cold fluid is needed.

16) The two tier design for a refrigeration unit as in claim 1, claim 3 and claim 10 wherein the thermometer is in state 3 and the timer is on. The valve is opened so that the storage compartment can be super cooled while there is cheap electricity and so store more coldness in the storage compartment.

17) The two tier design for a refrigeration unit as in claim 1 wherein the storage compartment has a substance in it which has a high specific heat or uses the latent heat of vaporisation or latent heat of fusion to store coldness in the structure of the fluid and enhance claim 16.

18) The two tier design for a refrigeration unit as in claim 17 wherein the storage compartment has a substance at the top of the refrigerator. This is so the warm air inside the compartment will rise up until it touches the heat storing substance cool and then sink mixing with the other air and preventing thermal layers from developing. in the storage compartment.

19) The two tier design for a refrigeration unit as in claim 1, claim 3 and claim 10 wherein the thermometer is in state 4. The cooling unit is turned off even if the timer is on and the valve is shut.

20) The two tier design for a refrigeration unit as in claim 1 wherein the storage compartment uses convection currents to move the fluid around the storage compartment.

21) The two tier design for a refrigeration unit as in claim 1 wherein the exchange unit uses convection currents to move the fluid from itself to the storage unit.

22) The two tier design for a refrigeration unit as in claim 1 wherein the storage compartment feeds warm fluid to the top of the storage unit and takes cold fluid from the bottom of the unit and therefore creates a thermal layers so that the warm fluid at the top which is less dense does not mix with the cold fluid at the bottom which has a greater density.

23) The two tier design for a refrigeration unit as described with reference to Fig 1.